The present invention relates to a phase analyzer, a phase analysis method, and a surface analyzer.
Phase analysis has been known as a method that analyzes elemental map data (intensity or concentration distribution data corresponding to each element) acquired using a surface analyzer such as an electron probe microanalyzer (EPMA). The term “phase analysis” refers to a method that extracts the phase of a compound from the correlation between a plurality of elements, and determines the correlation corresponding to each phase. For example, JP-A-2006-125952 discloses a surface analyzer that implements phase analysis that generates a scatter diagram based on concentration distribution data relating to a plurality of elements obtained from the area analysis results to estimate the presence of a compound or the like.
A process that generates a phase map (i.e., a diagram that shows the compound distribution) from elemental map data normally includes a map analysis (area analysis) step, an elemental map data readout step, a scatter diagram generation step, an uneven data distribution search step (that searches the scatter diagram for an uneven data distribution), and a phase map generation step. Each step is described below.
The map analysis step performs map analysis using a surface analyzer. The map analysis is performed by dividing a specified range of a sample into pixels (unit areas), and measuring the X-ray intensity at each pixel, for example. The elemental map data obtained by the map analysis is displayed as an image that represents the difference in X-ray intensity using a color (i.e., the difference in brightness or hue). FIG. 21 illustrates Al elemental map data, and FIG. 22 illustrates Ca elemental map data.
The elemental map data readout step reads the elemental map data by causing a computer to execute phase analysis software. The elemental map data of each element is read as intensity data having one column. For example, the elemental map data analyzed using 300×300 pixels has 90,000 rows.
In the scatter diagram generation step, the phase analysis software generates the scatter diagram based on the elemental map data. For example, when the user has selected two pieces of elemental map data from a plurality of pieces of elemental map data (that have been read), the phase analysis software plots the intensity data at each point of a scatter diagram in which the horizontal axis indicates one of the two pieces of elemental map data selected by the user, and the vertical axis indicates the other of the two pieces of elemental map data selected by the user. FIG. 23 illustrates a scatter diagram in which the horizontal axis indicates Al elemental map data, and the vertical axis indicates Ca elemental map data.
In the uneven data distribution search step, an uneven distribution is determined by changing the display color of the scatter diagram corresponding to the number of data points (see FIG. 24). In the example illustrated in FIG. 24, five uneven distributions are observed within the scatter diagram.
The phase map generation step encloses each uneven distribution, and applies a different color to each uneven distribution (see FIG. 25). Each color is reflected in the display state of the elemental map data to generate the phase map (see FIG. 26).
According to the above process, however, a number of steps are required to generate the phase map. In particular, the user must select an appropriate combination of elements from a large number of elements in the scatter diagram generation step, and determine the correlation between the elements. It is difficult for an inexperienced user to select an appropriate combination of elements, and determine the correlation between the elements. For example, it is necessary to try a large number of combinations (up to forty-five combinations when the number of pieces of elemental map data is 10) in order to find the most useful combination from ten pieces of elemental map data.